Hydrogen/Deuterium Exchange Kinetics by a Silica-Supported Zirconium Hydride Catalyst:  Evidence for a σ-Bond Metathesis Mechanism

Casty, Gary L.; Matturro, Michael G.; Myers, G. Rodney; Reynolds, and Robert P.; Hall, Richard B.

doi:10.1021/om0007926

Cited by 45 publications

(46 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A classical way to start probing the reactivity of a new complex is the investigation of its H/D exchange reactions: such a longstanding approach in the study of C-H and H-H bond activation and reaction mechanisms [17][18][19][20][21][22][23][24] is being extended, given the renewed interest in catalytic C-H activation [25][26][27] and novel applications of deuterium tags in biocatalysis [28][29][30][31] and analytical chemistry [32,33], leading to the current renaissance of the topic [34,35].…”

Section: Introductionmentioning

confidence: 99%

H/D Exchange on Silica-Grafted Tantalum(V) Imido Amido [(≡SiO)2Ta(V)(NH)(NH2)] Synthesized from Either Ammonia or Dinitrogen: IR and DFT Evidence for Heterolytic Splitting of D2

et al. 2009

View full text Add to dashboard Cite

The silica-grafted Ta (V) imido amido complex [(:SiO) 2 Ta(NH)(NH 2 )], 2, obtained from the reaction of either ammonia or dinitrogen plus hydrogen with the silicagrafted hydrides [(:SiO) 2 Ta (III) H], 1a, and [(:SiO) 2-Ta (V) H 3 ], 1b, undergoes H/D exchange with D 2 . In situ IR spectroscopy shows that the fully labelled compound [(:SiO) 2 Ta(ND)(ND 2 )], 2-d, can be obtained by moderate heating (60°C, 3 h) under D 2 atmosphere (550 torr, 300 eq. with respect to Ta), and that the exchange is reversible. The observed stretching and bending frequencies of 2-d are in agreement with the expected isotopic shift upon H/D replacement with respect to literature values reported for 2 and have been corroborated by the independent synthesis of 2-d by reaction of deuterated 1a and 1b with N 2 and D 2 . Density functional theory (DFT) calculations, performed using a periodic or a cluster model, explored the structures and energetics of all minima involved in the reaction with H 2 and showed that among the explored pathways the energetically preferred mechanisms for H 2 reaction with [{(l-O)[(HO) 2 SiO] 2 }Ta (V) (NH) (NH 2 )], 2q, is the heterolytic cleavage of either the imido Ta=N or the amido Ta-N bonds, to yield respectively [{(l-O)[(HO) 2 SiO] 2 }TaH(NH 2 ) 2 ], 3q (DE = -9.5 kcal mol -1 and DG 298K = ?2.6 kcal mol -1 with respect to 2q) and [{(l-O)[(HO) 2 SiO] 2 }Ta(NH) (NH 3 )], 4q (DE = -6.0 kcal mol -1 and DG 298K = ?7.9 kcal mol -1 with respect to 2q). All activation barriers are moderate (between 17.7 and 30.2 kcal mol -1 ) in agreement with the observed mild heating conditions necessary for the reaction to occur.

show abstract

Section: Introductionmentioning

confidence: 99%

H/D Exchange on Silica-Grafted Tantalum(V) Imido Amido [(≡SiO)2Ta(V)(NH)(NH2)] Synthesized from Either Ammonia or Dinitrogen: IR and DFT Evidence for Heterolytic Splitting of D2

et al. 2009

View full text Add to dashboard Cite

show abstract

“…Among such processes are the olefin polymerization [1][2][3][4][5][6][7], hydrogenation of olefins [8], isotope exchange in alkanes [9], as well as hydroisomerization and hydrogenolysis of alkanes [10][11][12][13][14]. The last two processes, which were experimentally investigated by Basset et al [8,[10][11][12][13][14][15][16][17], have been the focus of recent interest of researchers in the above-mentioned catalytic systems.…”

Section: Introductionmentioning

confidence: 99%

“…[8][9][10]15,16]) followed by heating to 423 K under hydrogen. Under these conditions, the system always contains a mixture of the surface-supported metal hydrides [7,16].…”

Section: Introductionmentioning

confidence: 99%

Hydrogenolysis of alkanes and olefin polymerization on the silica-supported zirconium hydrides: A comparative DFT study

Besedin

Ustynyuk

et al. 2005

Top Catal

View full text Add to dashboard Cite

The model reactions of ethylene polymerization and hydrogenolysis of linear alkanes (propane, n-butane, and n-pentane) on the silica-supported zirconium hydrides (BSiAO) 3 Zr IV H, (BSiAO) 2 Zr IV H 2 , and (BSiAO) 2 Zr III H were studied using the DFT approach. Catalytic processes under study were shown to occur involving different surface hydrides. The ethylene polymerization was found to proceed at comparable rates on the zirconium monohydrides, (BSiAO) 3 ZrH, and dihydrides, (BSiAO) 2 ZrH 2 . Cleavage of linear alkanes on the monohydrides (BSiAO) 3 ZrH is thermodynamically unfavorable; however, the dihydrides (BSiAO) 2 ZrH 2 can act as catalysts of the process under mild conditions. Hydrides of the trivalent zirconium, (BSiAO) 2 Zr III H, can also contribute to the hydrogenolysis reaction. A feature of all the systems studied is low regioselectivity of the corresponding processes.

show abstract

“…The compound Zr(NMe 2 ) 4 is an effective catalyst for this carbonyl hydroboration reaction, as is {PhB(Ox Me2 ) 2 C 5 H 4 }Zr(NMe 2 ) 2 . 46 In the presence of 5 mol % of either soluble complex, quantitative conversion of PhCHO to PhCH 2 OBpin is observed after 30 min in benzene-d 6 at 60°C…”

mentioning

confidence: 99%

Mesoporous Silica-Supported Amidozirconium-Catalyzed Carbonyl Hydroboration

et al. 2015

View full text Add to dashboard Cite

The hydroboration of aldehydes and ketones using a silica-supported zirconium catalyst is reported. Reaction of Zr(NMe2)4 and mesoporous silica nanoparticles (MSN) provides the catalytic material Zr(NMe2)n@MSN. Exhaustive characterization of Zr(NMe2)n@MSN with solid-state (SS)NMR and infrared spectroscopy, as well as through reactivity studies, suggests its surface structure is primarily ≡SiOZr(NMe2)3. The presence of these nitrogen-containing zirconium sites is supported by 15N NMR spectroscopy, including natural abundance 15N NMR measurements using dynamic nuclear polarization (DNP) SSNMR. The Zr(NMe2)n@MSN material reacts with pinacolborane (HBpin) to provide Me2NBpin and the material ZrH/Bpin@MSN that is composed of interacting surface-bonded zirconium hydride and surface-bonded borane ≡SiOBpin moieties in an approximately 1:1 ratio, as well as zirconium sites coordinated by dimethylamine. The ZrH/Bpin@MSN is characterized by 1H/2H and 11B SSNMR and infrared spectroscopy and through its reactivity with D2. The zirconium hydride material or the zirconium amide precursor Zr(NMe2)n@MSN catalyzes the selective hydroboration of aldehydes and ketones with HBpin in the presence of functional groups that are often reduced under hydroboration conditions or are sensitive to metal hydrides, including olefins, alkynes, nitro groups, halides, and ethers. Remarkably, this catalytic material may be recycled without loss of activity at least eight times, and air-exposed materials are catalytically active. Thus, these supported zirconium centers are robust catalytic sites for carbonyl reduction and that surface-supported, catalytically reactive zirconium hydride may be generated from zirconium-amide or zirconium alkoxide sites. ABSTRACT: The hydroboration of aldehydes and ketones using a silica-supported zirconium catalyst is reported. Reaction of Zr(NMe 2 ) 4 and mesoporous silica nanoparticles (MSN) provides the catalytic material Zr(NMe 2 ) n @MSN. Exhaustive characterization of Zr(NMe 2 ) n @MSN with solidstate (SS)NMR and infrared spectroscopy, as well as through reactivity studies, suggests its surface structure is primarily  SiOZr(NMe 2 ) 3 . The presence of these nitrogen-containing zirconium sites is supported by 15 N NMR spectroscopy, including natural abundance 15

show abstract

Hydrogen/Deuterium Exchange Kinetics by a Silica-Supported Zirconium Hydride Catalyst: Evidence for a σ-Bond Metathesis Mechanism

Cited by 45 publications

References 27 publications

H/D Exchange on Silica-Grafted Tantalum(V) Imido Amido [(≡SiO)2Ta(V)(NH)(NH2)] Synthesized from Either Ammonia or Dinitrogen: IR and DFT Evidence for Heterolytic Splitting of D2

H/D Exchange on Silica-Grafted Tantalum(V) Imido Amido [(≡SiO)2Ta(V)(NH)(NH2)] Synthesized from Either Ammonia or Dinitrogen: IR and DFT Evidence for Heterolytic Splitting of D2

Hydrogenolysis of alkanes and olefin polymerization on the silica-supported zirconium hydrides: A comparative DFT study

Mesoporous Silica-Supported Amidozirconium-Catalyzed Carbonyl Hydroboration

Contact Info

Product

Resources

About